Irma approached Naples on the state's west coast with maximum sustained winds of 120 miles per hour (195 kph), making it a risky Category 3 storm, according to the U.S. National Hurricane Center.
FPL said it had shut down one of Turkey Point's two nuclear reactors. Some customers who experienced outages Saturday and had their power restored - some 120,000 in Miami-Dade and Broward - could be hit again.
The improvements, utility representatives said, are designed not to prevent outages wholesale, but rather limit damage so that it is easier to restore lost power more quickly.
"It's going to get worse", Scott said.
The NRC inspectors are verifying that all of the preparations have been completed, and the plants' emergency diesel generators are available to be used if the storm affects off-site power supplies, the agency said in a statement. So far, that's about 1,000 more crew assembled for Hurricane Matthew in 2016.
Before Hurricane Irma's full force reached Central Florida thousands of residents along the Space Coast were already without power.
FPL also said it will proactively shut down certain substations before they flood, so they can turn them back online more quickly.
The electric utility can see whether a house or business is out of power even in the field via iPads, which utility restoration workers will be using in their work. At midafternoon local time, they reported only scattered outages.